Exposure-meter.



W. W. VENABLE.

' EXPOSURE METER. APPucATlou mso ris. 1s, |916.

IVVENTOR Patented Dec'. 5, 1916 le am:

. features of the invention will at A, B, C', etc.

. adjacent 'to the open1ngs'2. In the drawing film VI have-shown only vmake. These plates or UNITED sTATEs WILLIAM 'WALTERI VENBLE, 0F CHARLESTON, 'WEST VIRGINIA.

EXPOSURE-METER.

I Specification of Letters Patent. l

Patented Dee. 5, 1916.

Application flied February 16, 1916. Serial No. 78,632.

To all 'whom it may concern;

Be it known that I, WILLIAM W. VENABLE, a citizen of the United States, and a resident of Charleston, in the county of Kanawha and State of West Virginia, have invented certain Vnew and useful Improvements in Exposure-Meters, of which the following is a specification.

My invention relates toimprovements in exposure meters for use in photography, and it consists in the combinations, constructions, and varrangements herein described and claimed.

An object of my invention is to provide a simple and handy device by means of which the timeof exposure may be quickly ascertained under varyingv conditions of light, kind of plate or film used, time of the year, number of the stop, etc.

A further object of my invention is to provide a device of the type described which is exceedingly simple in operation, but which shows at a glance the exposure time for a whole series vofstop values, this seriesbeing arranged radially and being viewed througha panel or window.

Other objects and advantages will appear in the following specification, and the novel be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings forming part of this application, in which- Figure 1 is a face view of the device as assembled.- Fig. '2 is 4a section along the line 2-2 of Fig. 1. Fig. Bis a face view of one of the rotatable tables, and Fig. 4. is a perspective view of a movable transparent arm.

In carrying out base portion 1 which may consist of any suitable material, such as` cardboard. At the -top of the base 1 is. provided a series of holes 2 arranged on the arc ofa circle. It will be noted that these holes are provided with indicating marks, such as those shown Referring to the bottom of. the base portion, it will be seen that I have provided a partial list of plates and films of standard films have indicating letters which correspdxd with the letters a few of the names of the plates and films of standard make, but it will be understood that a'- comparatively my invention, I provide a,

small card is entirely sufficient for containing the names ofl all of the standard makes of plates or films in ordinary use.

Pivotally mounted at 3 is a circular plate 4, preferably of cardboard. and extending slightlybeyond the edgel of the base portion 1, while concentrically mounted is a circular disk 5 having a diameter less than that o-f the member 4. An arm 6 which is made of solne transparent material, such as celluloid or the like, is also pivotally mounted at 3, and is provided with an opening 7 arranged' to register with the openings 2 as the arm (5 is shifted on its pivo't 3. I find that it is convenient to make use of a flexible brass fastener for the pivot 3, and also4 to use a smaller fastener 8 to secure the arm 6 in its adjusted position, see Fig. 2.

Referring again to the base portion l, it4 will be seen that the light conditions are arranged in an arc concentric with the'disks 4, and 5. The disk 4 is provided on its outer edge with indicating marksl for indicating the kind of view to photographed. vThese are shown at 9. At 10A I have shown a table made up of concentric rows provided Uvith numerals and arranged in such a way that a series of radially extending tables'is formed, these tables indicating exposure times for particular stop values.

Upon the disk 5 is a series of concentric circles marked with the months of the year and'also with the hours of the day.

The plate arm 6 is provided with a window 6w which is arranged `to register with those numerals indicating the hours of the day and which, as will be seen, are formed in radiating tables similar to the exposure time.

The disk 5 is provided with a window or opening 5x and on each side thereof are stop values 12.

From the foregoing description of the various parts of the device, the operation thereof will bereadily understood.

With a device similar to that shown in Fig. 1, let us assume find lthe time of exposure for an average view, in bright sunlight, -at seven oclock a. m., on a day in April, with a 16 U. S. stop. Let us further assume that the' exposure is to be made on a Premo film pack AThe plate arm 6 is first moved to the position in .which the .opening 7 with the opening() in the base 1,'since that it is desired to lOl ' this is the lposition. which is indicated by noting thecharacter C after the@ Words Premo pack under the heading Films, at the bottom of the base member l. rlhe disk 4c is now turned until the designation i stop value 16 U. S. it will be observed that the time is given' as 'of a second.

other exposure time may be Obviously any similar procedure.

ascertained by.

I claim l. A time exposure meter for photographic purposes, which consists of a iat base, a circular disk mounted for rotation on said base, a 4second disk mounted for rotation .fon the ,face of said irst named disk, a pivoted arm mounted on said second.

extending tables, said circular disk, a rotatable arm mounted on the face of said second named circular disk,

vsaid disks and said arm having a common pivot .and saidarm projecting beyond the edge of said first named disk, said base having a series of holes'disposed in arc-shaped arrangement .concentric with said disks,

said arm being provided with an opening arranged to register with any of said holes and being provided with a Window, said rst named diskhaving a series of radially second named disk being provided With-an opening arranged to register With said tables and having a series of radially extending tablesarranged to register with the Window in said arm.

2. A time exposure meter for. photographic purposes, consisting of abase poi'- tion having a series of indicating marks arranged iu arc-shaped form, and a series of data indicating the kind of light arranged in arc-shaped form, a rotatable disk having on vits edge aseries of data indicating the kind of views,- a disk mounted on said first named .rotatable named rotatable disk, said disk and said 'arm having a common pivotal point'rand figures opposite the I ister With another second rotatable to register with one of said sets of indicati ing marks and being provided With a series of radially extending indicating second rotatable disk mounted on the face of the first rotatable disk, a rotatable arm having an indicating mark arranged to regset of indicating marks on said base, each of' said disks being provided With indicatingftables on the surface thereof, said arm having a Window arranged to expose the tables on said second named disk, and said second named disk .having a Window arranged to expose the tables on said first named disk.

tables, a

4. In an exposure meter, a base member having a plurality of sets of indicating marks arranged in arc-shaped form thereon, a rotatable disk mounted on said base member and having indicating marks arranged to register with one of said sets of @indicating marks and being provided with .extending indicating' a series of radially tables, a second rotatable disk mounted on the face of the first rotatable disk, a rotatable arm having an indicating mark arranged to register with another set of 1ndisks being provided Withindicating tables on the surface thereof, said arm having a Window arranged to expose the tables .on saidsecond named disk, and said second 'dicating marks on said base, each of said l named disk having a-Window arranged toexpose thetables on said rst named disk, -said second named disk also being provided with a series ofstop lvalue indicating marks on the edges ofthe window,'each of said marks corresponding to one of the f exposure time value marks on said irstnamed disk.

WILLIAM WiiLr'oN vENABLE. 

